Increasingly, big companies are bringing their marketing efforts in-house. It usually starts with a small, internal design group or a new Chief Creative Officer, which evolves into a whole department full of talented creatives. Inevitably, they ask themselves, “Why do we need an ad agency?”

I’ll tell you why.

First, let me disclose that I’ve worked in advertising agencies for most of my 20 year career. But, lest you think I’m biased, you should know that I’ve also worked as a freelancer for a number of years, often directly for in-house marketing departments. So I’ve experienced both worlds.

For years I dealt with this question, mostly in response to clients who wanted to dictate creative ideas. Or change the ones we developed for them. It was frustrating because we were the ones with the expertise. But more importantly, we had something they couldn’t acquire: objectivity.

Expertise is one important reason why a company should have an ad agency on retainer. But since agencies can’t corner the market on talent, I’ll focus on the importance of objectivity. This is a critical attribute that is totally unobtainable by in-house marketing teams.

Every company is like a new mother who thinks their baby is the most beautiful child in the world. Even though everyone else can see it is not. If you work in-house, no matter how hard you try, you will never be able to distance yourself from your brand in order to really see things objectively.

Why am I so sure? Because, ultimately, your allegiance is to your paycheck. Which means it’s virtually impossible to take risks that will enable your brand to be surprising and innovative.

Pretty much all company men (and women) are bobbleheads. Even when they think they’re independent, analytical, contrarian thinkers, who aren’t afraid to disagree with their bosses, they eventually conform to senior management. Especially when their job is on the line.

I know because it takes a former bobblehead to know a bobblehead. I’m a creative person by trade and we creatives are anti-conformists by nature. However, when you come home at night and look into your toddler’s eyes or kick back on your designer sofa with a fifty dollar bottle of wine, you get an eye-full of what you’re risking if you push senior management beyond their comfort zone. And so you ease up. I don’t like to admit it, but it’s true. It’s human nature.

There are only a handful of people on the planet that are seemingly immune to the fear of getting fired or making a mistake. These people are rarely ever employed as company men. They work for themselves as entrepreneurs. Everything they do is risky. It’s a way of life.

You might ask, since an ad agency is essentially employed by a company as well, aren’t they just as much afraid of getting fired and therefore less apt to push their clients into an uncomfortable place? Well, yes, the bad advertising agencies do whatever their clients want.

However, the good ones don’t. For this reason: their reputation is more important than the monthly retainer. In the long run, clients will come and go. But an agency’s reputation is their livelihood. That’s why the best ad agencies say the tough things. They argue with clients. They push them. They even resign accounts. All because they have integrity.

You’re welcome to disagree with me, but you’d be wrong. Ask yourself, do you respect a “yes man”? If you can honestly answer yes, I don’t believe you.

Nobody respects a yes man. We all value the truth, even when it hurts our ego. Because after the sting wears off we appreciate the critical comments and can make strides to improve ourselves and correct our course. That’s the power of objectivity.

When you’re an in-house company man, you’re staunchly loyal to your company. Er, um, your paycheck. So the only way to benefit from true objectivity is to retain an ad agency. If they’re good, they’ll tell you what you need to hear, not what you want to hear. And that is worth much more than what you pay them.

Long live great ad agencies that have the courage to stand for something. And long live great clients that are brave and trusting. Together they can move mountains.